Compact distributed fiber SPR sensor based on TDM and WDM technology.

By using a twin-core fiber (TCF), we propose and demonstrate a novel distributed SPR sensor, which employs both the time division multiplexing (TDM) technology and the wavelength division multiplexing (WDM) technology together. The proposed sensor has two sensing passages with four sensing channels (and there are two sensing channels in each sensing passage). We employ the TDM technology to realize the two passage distributed sensing, which are parallel-connection; and we employ the WDM technology to realize the distributed sensing of two channels in a sensing passage, which are series-connected. In order to realize the TDM technology, we employ a two-core fiber, which has two cores in a same cladding, being equal to dividing the traditional single core into two independent sensing zones; in order to realize the WDM technology, we employ a fiber end polishing-connecting method to adjust the resonance angle/wavelength to realize the dynamic range separation. This twin-passage four-channel twin-core fiber SPR sensor is suitable for applying in fields of the multi-channel liquid refractive index and temperature self-reference measurement.